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LibDebug: Implement ability to set watchpoints

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Now we can set hardware watchpoints for our variables! :^)
These watchpoints will be automatically removed when
they go out of scope.
This commit is contained in:
FalseHonesty 2021-04-15 12:40:17 -04:00 • committed by Andreas Kling
parent 3123ffb19d
commit 7a1396f509
3 changed files with 145 additions and 0 deletions
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54
Userland/Libraries/LibDebug/DebugSession.h
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@ -54,6 +54,9 @@ public:
bool poke(u32* address, u32 data);
Optional<u32> peek(u32* address) const;
bool poke_debug(u32 register_index, u32 data);
Optional<u32> peek_debug(u32 register_index) const;
enum class BreakPointState {
Enabled,
Disabled,
@ -87,6 +90,17 @@ public:
bool remove_breakpoint(void* address);
bool breakpoint_exists(void* address) const;
struct WatchPoint {
void* address { nullptr };
u32 debug_register_index { 0 };
u32 ebp { 0 };
};
bool insert_watchpoint(void* address, u32 ebp);
bool remove_watchpoint(void* address);
bool disable_watchpoint(void* address);
bool watchpoint_exists(void* address) const;
void dump_breakpoints()
{
for (auto addr : m_breakpoints.keys()) {
@ -182,6 +196,7 @@ private:
bool m_is_debuggee_dead { false };
HashMap<void*, BreakPoint> m_breakpoints;
HashMap<void*, WatchPoint> m_watchpoints;
// Maps from base address to loaded library
HashMap<String, NonnullOwnPtr<LoadedLibrary>> m_loaded_libraries;
@ -223,6 +238,45 @@ void DebugSession::run(DesiredInitialDebugeeState initial_debugee_state, Callbac
state = State::FreeRun;
auto regs = get_registers();
auto debug_status = peek_debug(DEBUG_STATUS_REGISTER);
if (debug_status.has_value() && (debug_status.value() & 0b1111) > 0) {
// Tripped a watchpoint
auto watchpoint_index = debug_status.value() & 0b1111;
Optional<WatchPoint> watchpoint {};
for (auto wp : m_watchpoints) {
if ((watchpoint_index & (1 << wp.value.debug_register_index)) == 0)
continue;
watchpoint = wp.value;
break;
}
if (watchpoint.has_value()) {
auto required_ebp = watchpoint.value().ebp;
auto found_ebp = false;
u32 current_ebp = regs.ebp;
u32 current_instruction = regs.eip;
do {
if (current_ebp == required_ebp) {
found_ebp = true;
break;
}
auto return_address = peek(reinterpret_cast<u32*>(current_ebp + sizeof(FlatPtr)));
auto next_ebp = peek(reinterpret_cast<u32*>(current_ebp));
VERIFY(return_address.has_value());
VERIFY(next_ebp.has_value());
current_instruction = return_address.value();
current_ebp = next_ebp.value();
} while (current_ebp && current_instruction);
if (!found_ebp) {
dbgln("Removing watchpoint at {:p} because it went out of scope!", watchpoint.value().address);
remove_watchpoint(watchpoint.value().address);
continue;
}
}
}
Optional<BreakPoint> current_breakpoint;
if (state == State::FreeRun || state == State::Syscall) {